/Engine/Source/Runtime/Core/Public/UObject/WeakObjectPtrTemplates.h
MapKeyFuncs for TWeakObjectPtrs which allow the key to become stale without invalidating the map.
template<typename KeyType, typename ValueType, bool bInAllowDuplicateKeys> struct TWeakObjectPtrMapKeyFuncs : public [TDefaultMapKeyFuncs< KeyType, ValueType, bInAllowDuplicateKeys >](API\Runtime\Core\Containers\TDefaultMapKeyFuncs)